Video coding method and apparatus

ABSTRACT

The present invention relates to a method and apparatus for performing encoding and decoding using a variably-sized quantization coefficient group, in quantization coefficient group encoding and decoding of video compression technology.

CROSS REFERENCE TO RELATED APPLICATION

This present application is a continuation of U.S. application Ser. No.16/084,105, filed Sep. 11, 2018, which is a national stage filing under35 U.S.C § 371 of PCT application number PCT/KR2017/002578 filed on Mar.9, 2017 which is based upon and claims the benefit of priority to KoreanPatent Application Nos. 10-2016-0029699 filed on Mar. 11, 2016,10-2016-0031800 filed on Mar. 17, 2016, 10-2016-0038075 filed on Mar.30, 2016, 10-2016-0048883 filed on Apr. 21, 2016, and 10-2016-0054609filed on May 3, 2016 in the Korean Intellectual Property Office. Thedisclosures of the above-listed applications are hereby incorporated byreference herein in their entireties.

TECHNICAL FIELD

The present invention relates to image processing technology.

BACKGROUND ART

Recently, as demands for high-resolution and high-quality video haveincreased, high-efficiency video compression technology fornext-generation video services is necessary.

In the video compression technology, quantization coefficient encodingand decoding technologies mean technology of generating a bitstreamthrough entropy encoding technology performed on a signal subjected totransform and quantization with respect to a difference signal betweenan original signal and a prediction signal or technology ofreconstructing the generated bitstream into the difference signalthrough entropy decoding technology.

DISCLOSURE Technical Problem

An object of the present invention is to provide a method and apparatusfor enhancing encoding efficiency in association with video compressiontechnology.

Another object of the present invention is to provide a method andapparatus in which a decoder derives information on a motion vector andthis enables video encoding/decoding to be performed effectively in sucha manner that a video encoder/decoder for high-resolution images such asfull-high-definition (FHD) images and ultra-high-definition (UHD) imageseffectively transmits motion information.

Another object of an embodiment of the present invention is to provide amethod and apparatus for performing global motion compensation on anextensive region in an image.

Another object of an embodiment of the present invention is to provide amethod and apparatus for generating a reference signal to effectivelyperform intra prediction.

Another object of an embodiment of the present invention is to provide amethod and apparatus using a curve intra prediction technique in thevideo compression technology.

However, it is to be understood that technical problems to be solved bythe present disclosure are not limited to the aforementioned technicalproblems and other technical problems may be present.

Technical Solution

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: aquantization coefficient group information obtainment module obtaininginformation on a quantization coefficient group for inversequantization; a quantization coefficient group entropy decoding moduleobtaining quantization coefficients through entropy decoding on thequantization coefficient group; an inverse quantization module obtainingtransform coefficients through inverse quantization on the obtainedquantization coefficients; and an inverse transform module obtainingdifference signals through an inverse transform process on the obtainedtransform coefficients.

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: avariably-sized quantization coefficient group usage extraction moduleextracting information on whether a variably-sized quantizationcoefficient group is used with respect to a current decoding bitstream,from the bitstream; a quantization coefficient group partitioninformation decoding module obtaining partition information on thequantization coefficient group for inverse quantization in a currentdecoding unit when the extracted information on whether thevariably-sized quantization coefficient group is used indicates that thevariably-sized quantization coefficient group is used; and aquantization coefficient entropy decoding module performing quantizationcoefficient entropy decoding.

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: aquantization coefficient group partition flag extraction moduleextracting a quantization coefficient group partition flag with respectto partition from a bitstream on the basis of a size of a currentdecoding unit; a quantization coefficient group size determinationmodule determining a size of the quantization coefficient group in thecurrent decoding unit when the extracted quantization coefficient grouppartition flag indicates non-partition; a sub quantization coefficientgroup partition module partitioning the current decoding unit intomultiple sub quantization coefficient groups when the extractedquantization coefficient group partition flag indicates partition; and aquantization coefficient group entropy decoding module performingquantization coefficient group entropy decoding.

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: avariably-sized quantization coefficient group usage extraction moduleextracting information on whether a variably-sized quantizationcoefficient group is used with respect to a current decoding bitstream,from the bitstream; a quantization coefficient group partition methoddetermination module determining a method of partitioning thevariably-sized quantization coefficient group when the extractedinformation on whether the variably-sized quantization coefficient groupis used indicates that the variably-sized quantization coefficient groupis used; and a quantization coefficient group size informationobtainment module obtaining information on a size of the quantizationcoefficient group for inverse quantization in a current decoding unitaccording to the determined method of partitioning the variably-sizedquantization coefficient group.

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: aquantization coefficient group partition number information extractionmodule extracting quantization coefficient group partition numberinformation with respect to partition from a bitstream on the basis of asize of a current decoding unit; and a quantization coefficient grouppartition module partitioning a quantization coefficient group usingpartition information defined on the basis of a method of partitioning avariably-sized quantization coefficient group, the size of the currentdecoding unit, and the quantization coefficient group partition numberinformation.

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: avariably-sized quantization coefficient group usage informationextraction module extracting information on whether a variably-sizedquantization coefficient group is used with respect to a currentdecoding bitstream, from the bitstream; a quantization coefficient grouppartition information obtainment module obtaining partition informationof the quantization coefficient group for inverse quantization in acurrent decoding unit when the extracted information on whether thevariably-sized quantization coefficient group is used indicates that thevariably-sized quantization coefficient group is used; and an entropydecoding scanning order obtainment module obtaining an entropy decodingscanning order of the quantization coefficient group on the basis ofpartition information on the quantization coefficient group for inversequantization.

In order to accomplish the above objects, according to an embodiment ofthe present invention, the video decoding apparatus and method include amotion information derivation unit or step, and a decoder may derivemotion information without information on a motion vector directlyreceived from an encoder.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: obtaining information for global motion compensationfrom a bitstream; determining a global motion compensation region usingthe information for global motion compensation; and performing globalmotion compensation on the determined global motion compensation region.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: extracting a flag indicating whether global motioncompensation is used from a bitstream; determining a global motioncompensation region from the bitstream when the extracted flag indicatesuse of global motion compensation; and extracting information forperforming motion compensation on each determined global motion region.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: extracting a flag indicating whether global motioncompensation is used from a bitstream; and performing motioncompensation on a per-coding block basis when the extracted flagindicates non-use of global motion compensation.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: determining a region subjected to global motioncompensation using motion compensation region determination informationobtained from a bitstream; and performing motion compensation on eachdetermined region subjected to motion compensation.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: performing global motion compensation on each globalmotion compensation region using performance information for each motioncompensation region obtained from a bitstream.

As technical means for achieving the above technical objects, accordingto an embodiment of the present invention, in performing intraprediction, an image decoding method and apparatus may generate a signalon an unreconstructed region using a neighboring reconstruction signalreferenced for intra prediction such that effective intra prediction isperformed. Also, a range to be referenced for intra prediction in areconstructed signal is expanded compared with a conventional range suchthat many more reconstruction pixels are referenced. Accordingly, intraprediction performance is enhanced.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: extracting information for generating a predictionsignal from a bitstream; performing reference sample padding using theextracted information; generating a prediction sample by performingcurve intra prediction using the extracted information; and performingfiltering on the generated prediction sample.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: obtaining information for generating a prediction signalfrom a bitstream; and extracting information on curve intra predictionfrom the bitstream when the extracted intra prediction mode informationindicates curve intra prediction.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: determining whether to perform reference sample paddingusing information on curve intra prediction obtained from a bitstreamand information on whether a reference sample of a neighboring block ispresent; and performing reference sample padding.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include generating a prediction sample using information on curveintra prediction obtained from a bitstream.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include performing filtering using a variation in a neighboringreference sample when with respect to a left prediction sample columnand a top prediction sample row of a generated prediction block, aregion containing the sample column is subjected to horizontal directionprediction or vertical direction prediction.

Advantageous Effects

The present invention is intended to provide a method and apparatus thatuse a quantization coefficient group that is in variable size dependingon the characteristics of a signal and use an encoding and decodingorder corresponding thereto, whereby quantization coefficient encodingefficiency is enhanced.

According to the embodiment of the present invention, the variably-sizedquantization coefficient group and selective coefficient encoding anddecoding order are used to increase the number of coefficients excludedfrom encoding, whereby performance of quantization coefficient encodingis enhanced.

Also, according to the embodiment of the present invention, thequantization coefficient group varies in size and shape so that anenergy concentration effect by transform and quantization and a highfrequency component removal effect are obtained, whereby performance ofcoefficient encoding is enhanced.

According to the above-described technical solution of the presentinvention, in the decoder, a motion information derivation unit or stepenables video decoding without direct transmission of a motion vector,whereby video encoding/decoding efficiency is enhanced.

The present invention is intended to propose a method and apparatus forperforming global motion compensation on an extensive region in a motioncompensation process used in a conventional video compression technologyso as to enhance encoding efficiency.

According to an embodiment of the present invention, motion compensationis performed on an extensive region at once, and information on a globalmotion compensation region is effectively transmitted to the decoder,thereby enhancing encoding performance.

According to the above-described technical solution of the presentinvention, the decoder generates the intra prediction signal and expandsa reference range so that intra prediction performance is enhanced,whereby overall performance of video compression performance isenhanced.

The present invention is intended to propose a method and apparatus forperforming curve intra prediction in an intra prediction process used inthe conventional video compression technology so as to enhanceencoding/decoding efficiency.

According to the above-described technical solution of the presentinvention, curve intra prediction enhances intra prediction efficiencyin the encoder/decoder so that video compression performance isenhanced.

DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating configuration of a video decodingapparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a sequence of decoding avariably-sized quantization group according to an embodiment of thepresent invention.

FIG. 3 is a block diagram illustrating a sequence of determining whethera variably-sized quantization coefficient group is decoded and obtainingquantization coefficient group partition information according to anembodiment of the present invention.

FIG. 4 is a block diagram illustrating a sequence of decoding using avariably-sized quantization group partition flag according to anembodiment of the present invention.

FIGS. 5 and 6 are schematic diagrams illustrating examples ofquantization coefficient groups in a 4×4 fixed size and scanning ordersfor an 8×8 decoding block and a 16×16 decoding block using the groups.

FIG. 7 is a schematic diagram illustrating examples of using a quad-treeconfiguration and multiple scanning orders with respect to avariably-sized quantization coefficient group according to an embodimentof the present invention.

FIG. 8 is a schematic diagram illustrating examples of quad-treepartition of a 16×16 decoding block and a 32×32 decoding block for avariably-sized quantization coefficient group according to an embodimentof the present invention.

FIG. 9 is a schematic diagram illustrating examples of partitioning avariably-sized quantization coefficient group depending on input signalcharacteristics except for a square shape according to an embodiment ofthe present invention.

FIG. 10 is a schematic diagram illustrating a variably-sizedquantization coefficient group in a non-square shape according to anembodiment of the present invention.

FIG. 11 is a block diagram illustrating a decoding apparatus accordingto an embodiment of the present invention.

FIG. 12 is a flow chart illustrating motion derivation and motioncompensation in a decoding unit subjected to motion derivation.

FIG. 13 is a diagram illustrating examples of partitioning into subblocks when partitioning a decoding unit according to an embodiment ofthe present invention.

FIG. 14 is a diagram illustrating shapes of a neighboring pixelsubjected to motion prediction in an example in which motion derivationis performed using neighboring pixel information on a decoding unit.

FIG. 15 is a diagram illustrating an embodiment in which the method inFIG. 14 is performed using two reference images.

FIG. 16 is a diagram illustrating a method of deriving motion of acurrent decoding unit through motion prediction of co-located blocksusing two reference images.

FIG. 17 is a diagram illustrating a decoding apparatus that performsglobal motion compensation according to an embodiment of the presentinvention.

FIG. 18 is a diagram illustrating a method of performing global motioncompensation on an image according to an embodiment of the presentinvention.

FIG. 19 is a block diagram illustrating a sequence of a method ofperforming global motion compensation according to an embodiment of thepresent invention.

FIG. 20 is a diagram illustrating a method of determining a final globalmotion compensation region using information indicating an inside or anoutside of a region determined as a global motion compensation regionamong pieces of information transmitted to a decoder, when performingglobal motion compensation according to an embodiment of the presentinvention.

FIG. 21 is a diagram illustrating global motion compensation regions invarious shapes when performing global motion compensation according toan embodiment of the present invention.

FIG. 22 is a diagram illustrating a method of determining a globalmotion compensation region according to boundaries on a per-coding unitbasis when performing global motion compensation according to anembodiment of the present invention.

FIG. 23 is a diagram illustrating a method of determining a position ofa global motion compensation region when performing global motioncompensation according to an embodiment of the present invention.

FIG. 24 is a diagram illustrating a method of determining a globalmotion compensation region by merging sections obtained throughpartition in a grid shape, when performing global motion compensationaccording to an embodiment of the present invention.

FIG. 25 is a diagram illustrating a method of determining a globalmotion compensation region by repeatedly partitioning an image in ahorizontal or vertical direction, when performing global motioncompensation according to an embodiment of the present invention.

FIG. 26 is a diagram illustrating a method of determining a globalmotion compensation region using a warping parameter in additioninformation transmitted to a decoder when performing global motioncompensation according to an embodiment of the present invention.

FIG. 27 is a diagram illustrating a method of rotating or scaling aglobal motion compensation region when performing global motioncompensation according to an embodiment of the present invention.

FIG. 28 is a diagram illustrating a case in which a frame rate upconversion (FRUC) method for increasing a frame rate is used whenperforming global motion compensation according to an embodiment of thepresent invention.

FIG. 29 is a diagram illustrating a video decoding apparatus capable ofgenerating an intra prediction signal using intra prediction informationin an encoded bitstream and of outputting a reconstruction image usingthe generated intra prediction signal according to an embodiment of thepresent invention.

FIG. 30 is a diagram illustrating a referable region for an intraprediction block according to an embodiment of the present invention.

FIG. 31 is a diagram illustrating a method of performing directionalintra prediction depending on a length of a reference pixel columnaccording to an intra prediction method according to an embodiment ofthe present invention.

FIG. 32 is a diagram illustrating a method of performing directionalintra prediction depending on a length of a left pixel column accordingto an intra prediction method according to an embodiment of the presentinvention.

FIG. 33 is a diagram illustrating ranges of applicable directionalprediction in an intra prediction method according to an embodiment ofthe present invention.

FIG. 34 is a diagram illustrating a method of generating an intraprediction signal by varying a brightness of a pixel with the same slopeas a reconstruction pixel region from a signal of a neighboringreconstruction pixel region depending on pixel coordinates of anon-reconstruction pixel region in an intra prediction method accordingto an embodiment of the present invention.

FIG. 35 is a diagram illustrating a method of generating an intraprediction signal by varying a brightness of a pixel with a negativeslope having the same size as a reconstruction pixel region depending onpixel coordinates of a non-reconstruction pixel region from a signal ofa neighboring reconstruction pixel region in an intra prediction methodaccording to an embodiment of the present invention.

FIG. 36 is a diagram illustrating another method of generating an intraprediction signal by varying a brightness of a pixel with the same slopeas a reconstruction pixel region from a signal of a neighboringreconstruction pixel region depending on pixel coordinates of anon-reconstruction pixel region in an intra prediction method accordingto an embodiment of the present invention.

FIG. 37 is a diagram illustrating a method of signaling whether intraprediction is performed which is proposed by a sequence parameter set ofa high-level syntax for an intra prediction method according to anembodiment of the present invention.

FIG. 38 is a diagram illustrating a method of signaling whether intraprediction is performed which is proposed by a picture parameter set ofa high-level syntax for an intra prediction method according to anembodiment of the present invention.

FIG. 39 is a diagram illustrating a method of signaling whether intraprediction is performed which is proposed by a slice segment header of ahigh-level syntax for an intra prediction method according to anembodiment of the present invention.

FIG. 40 is a diagram illustrating a decoding apparatus including anintra prediction module according to an embodiment of the presentinvention.

FIG. 41 is a diagram illustrating neighboring reference regions whenperforming intra prediction according to an embodiment of the presentinvention.

FIG. 42 is a diagram illustrating a method of referring to a pixel of aneighboring block when performing intra prediction according to anembodiment of the present invention.

FIG. 43 is a diagram illustrating a method of referring to multiplepixels of a neighboring block when performing intra prediction accordingto an embodiment of the present invention.

FIG. 44 is a diagram illustrating a method of generating a non-existingreference sample in a neighboring block, when performing intraprediction according to an embodiment of the present invention.

FIG. 45 is a diagram illustrating a method of performing predictionusing reference samples in different directions in respective regions ofa prediction block, when performing intra prediction according to anembodiment of the present invention.

FIG. 46 is a diagram illustrating another method of performingprediction using reference samples in different directions in respectiveregions of a prediction block, when performing intra predictionaccording to an embodiment of the present invention.

FIG. 47 is a diagram illustrating a method of performing filtering on aleftmost prediction sample column of a prediction block so as to removediscontinuity to a neighboring block, when performing intra predictionaccording to an embodiment of the present invention.

FIG. 48 is a diagram illustrating a method of filtering a topmostprediction sample column of a prediction block so as to removediscontinuity to a neighboring block, when performing intra predictionaccording to an embodiment of the present invention.

FIG. 49 is a flowchart illustrating a sequence of performing intraprediction according to an embodiment of the present invention.

BEST MODE

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: aquantization coefficient group information obtainment module obtaininginformation on a quantization coefficient group for inversequantization; a quantization coefficient group entropy decoding moduleobtaining quantization coefficients through entropy decoding on thequantization coefficient group; an inverse quantization module obtainingtransform coefficients through inverse quantization on the obtainedquantization coefficients; and an inverse transform module obtainingdifference signals through an inverse transform process on the obtainedtransform coefficients.

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: avariably-sized quantization coefficient group usage extraction moduleextracting information on whether a variably-sized quantizationcoefficient group is used with respect to a current decoding bitstream,from the bitstream; a quantization coefficient group partitioninformation decoding module obtaining partition information on thequantization coefficient group for inverse quantization in a currentdecoding unit when the extracted information on whether thevariably-sized quantization coefficient group is used indicates that thevariably-sized quantization coefficient group is used; and aquantization coefficient entropy decoding module performing quantizationcoefficient entropy decoding.

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: aquantization coefficient group partition flag extraction moduleextracting a quantization coefficient group partition flag with respectto partition from a bitstream on the basis of a size of a currentdecoding unit; a quantization coefficient group size determinationmodule determining a size of the quantization coefficient group in thecurrent decoding unit when the extracted quantization coefficient grouppartition flag indicates non-partition; a sub quantization coefficientgroup partition module partitioning the current decoding unit intomultiple sub quantization coefficient groups when the extractedquantization coefficient group partition flag indicates partition; and aquantization coefficient group entropy decoding module performingquantization coefficient group entropy decoding.

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: avariably-sized quantization coefficient group usage extraction moduleextracting information on whether a variably-sized quantizationcoefficient group is used with respect to a current decoding bitstream,from the bitstream; a quantization coefficient group partition methoddetermination module determining a method of partitioning thevariably-sized quantization coefficient group when the extractedinformation on whether the variably-sized quantization coefficient groupis used indicates that the variably-sized quantization coefficient groupis used; and a quantization coefficient group size informationobtainment module obtaining information on a size of the quantizationcoefficient group for inverse quantization in a current decoding unitaccording to the determined method of partitioning the variably-sizedquantization coefficient group.

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: aquantization coefficient group partition number information extractionmodule extracting quantization coefficient group partition numberinformation with respect to partition from a bitstream on the basis of asize of a current decoding unit; and a quantization coefficient grouppartition module partitioning a quantization coefficient group usingpartition information defined on the basis of a method of partitioning avariably-sized quantization coefficient group, the size of the currentdecoding unit, and the quantization coefficient group partition numberinformation.

In order to accomplish the above objects, according to an embodiment ofthe present invention, a video decoding apparatus and method include: avariably-sized quantization coefficient group usage informationextraction module extracting information on whether a variably-sizedquantization coefficient group is used with respect to a currentdecoding bitstream, from the bitstream; a quantization coefficient grouppartition information obtainment module obtaining partition informationof the quantization coefficient group for inverse quantization in acurrent decoding unit when the extracted information on whether thevariably-sized quantization coefficient group is used indicates that thevariably-sized quantization coefficient group is used; and an entropydecoding scanning order obtainment module obtaining an entropy decodingscanning order of the quantization coefficient group on the basis ofpartition information on the quantization coefficient group for inversequantization.

In order to accomplish the above objects, according to an embodiment ofthe present invention, the video decoding apparatus and method include amotion information derivation unit or step, and a decoder may derivemotion information without information on a motion vector directlyreceived from an encoder.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: obtaining information for global motion compensationfrom a bitstream; determining a global motion compensation region usingthe information for global motion compensation; and performing globalmotion compensation on the determined global motion compensation region.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: extracting a flag indicating whether global motioncompensation is used from a bitstream; determining a global motioncompensation region from the bitstream when the extracted flag indicatesuse of global motion compensation; and extracting information forperforming motion compensation on each determined global motion region.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: extracting a flag indicating whether global motioncompensation is used from a bitstream; and performing motioncompensation on a per-coding block basis when the extracted flagindicates non-use of global motion compensation.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: determining a region subjected to global motioncompensation using motion compensation region determination informationobtained from a bitstream; and performing motion compensation on eachdetermined region subjected to motion compensation.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: performing global motion compensation on each globalmotion compensation region using performance information for each motioncompensation region obtained from a bitstream.

As technical means for achieving the above technical objects, accordingto an embodiment of the present invention, in performing intraprediction, an image decoding method and apparatus may generate a signalon an unreconstructed region using a neighboring reconstruction signalreferenced for intra prediction such that effective intra prediction isperformed. Also, a range to be referenced for intra prediction in areconstructed signal is expanded compared with a conventional range suchthat much more reconstruction pixels are referenced, thereby intraprediction performance is enhanced.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: extracting information for generating a predictionsignal from a bitstream; performing reference sample padding using theextracted information; generating a prediction sample by performingcurve intra prediction using the extracted information; and performingfiltering on the generated prediction sample.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: obtaining information for generating a prediction signalfrom a bitstream; and extracting information on curve intra predictionfrom the bitstream when the extracted intra prediction mode informationindicates curve intra prediction.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include: determining whether to perform reference sample paddingusing information on curve intra prediction obtained from a bitstreamand information on whether a reference sample of a neighboring block ispresent; and performing reference sample padding.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include generating a prediction sample using information on curveintra prediction obtained from a bitstream.

As technical means for achieving the above objects, according to anembodiment of the present invention, an image decoding apparatus andmethod include performing filtering using a variation in a neighboringreference sample when with respect to a left prediction sample columnand a top prediction sample row of a generated prediction block, aregion containing the sample column is subjected to horizontal directionprediction or vertical direction prediction.

MODE FOR INVENTION

Hereinbelow, exemplary embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings suchthat the invention can be easily embodied by those skilled in the art towhich this invention belongs. However, the present invention may beembodied in various different forms and should not be limited to theembodiments set forth herein. In order to clearly describe the presentinvention, parts not related to the description are omitted in theaccompanying drawings, and similar elements are denoted by similarreference numerals throughout the description.

Throughout the description, when a part is referred to as beingconnected to another part, it includes not only being directlyconnected, but also being electrically connected by interposing theother part therebetween.

Also, throughout the description, it should also be understood that whena component includes an element, unless there is another oppositedescription thereto, the component does not exclude another element butmay further include the other element.

Throughout the description, the term step of does not mean step for.

Also, it should also be understood that, although the terms first,second, etc. may be used herein to describe various elements, theseelements should not be limited by these terms. These terms are only usedto distinguish one element from another element.

Moreover, constituent parts described in the embodiments of the presentinvention are independently shown so as to represent characteristicfeatures different from each other. Thus, it does not mean that eachconstituent part is constituted in a constitutional unit of separatedhardware or software. That is, each constituent part includes each ofenumerated constituent parts for convenience. Thus, at least twoconstituent parts of each constituent part may be combined to form oneconstituent part or one constituent part may be divided into a pluralityof constituent parts to perform each function. The embodiment where eachconstituent part is combined and the embodiment where one constituentpart is divided are also included in the scope of the present invention,if not departing from the essence of the present invention.

Also, some of elements are not indispensable elements which performessential functions in the present invention but optional elements forjust enhancing the performance thereof. The present invention may beimplemented by including only the indispensable constituent parts forimplementing the essence of the present invention except the elementsused in improving performance. The structure including only theindispensable elements except the optional elements used in improvingonly performance is also included in the scope of the present invention.

A block used in the present invention may be a basic block unit, aprediction block unit, and a transform block unit in decoding. Also, ablock boundary may be a boundary of a decoding block, a boundary of aprediction block, and a boundary of a transform block.

First, terms used in the present application are briefly described asfollows.

Hereinafter, a video decoding apparatus may be an apparatus included ina personal computer (PC), a notebook computer, a portable multimediaplayer (PMP), a wireless communication terminal, a smart phone, and aserver terminal such as a TV application server, a service server, andthe like. Also, the video decoding apparatus may mean an apparatus,which may be provided in various types, including: various devices, suchas a user terminal, and the like; a communication device, and the like,such as a communication modem for performing communication via awired/wireless communication network; a memory storing various programsand data for decoding an image or for inter or intra prediction todecode the image; and a microprocessor executing programs forcalculation and control.

Also, the encoded image in bitstreams by an encoder may be transmittedto an image decoding apparatus in real-time or not in real-time via thewired/wireless communication network, such as the Internet, a wirelesslocal area network, a WiBro network, a mobile network, and the like, orvia various communication interfaces, such as a cable, a universalserial bus (USB), and the like, and the encoded image may be decoded andreconstructed into an image for display.

In general, a video may be composed of a series of pictures, and eachpicture may be partitioned into coding units such as blocks. Also, theterm a picture described below may be replaced with another term animage, a frame, or the like having the same meaning, which may beunderstood by those skilled in the art to which the embodiments belong.

Global motion compensation means a method of performing motioncompensation on an extensive region at once. A method of performingglobal motion compensation is referred to as a global motioncompensation method, and a region on which global motion compensation isperformed is referred to as a global motion compensation region.

Hereinafter, in various embodiments of the present invention describedin the description, “a quantization coefficient group” refers to a unitof processing a quantization transform coefficient which has beensubjected to transform and quantization processes, and may inclusivelyrefer to a group of transform signals subjected to only transform, agroup of quantization signal subject to only the quantization process,and a group of signal not subjected to both transform and quantization.

Hereinafter, according to an embodiment of the present invention, avideo decoding apparatus and method in which a variably-sizedquantization coefficient group is included will be described in detail.

FIG. 1 is a block diagram illustrating configuration of a video decodingapparatus and method according to an embodiment of the presentinvention.

According to an embodiment of the present invention, the video decodingapparatus and method may include at least one of an entropy decodingmodule 110, an inverse quantization module 120, an inverse transformmodule 130, an intra prediction module 140, an inter prediction module150, an adder 160, an in-loop filter module 170, and a reconstructionpicture buffer 180.

The entropy decoding module 110 decodes an input bitstream 100 so thatdecoding information, such as syntax elements, a quantized coefficient,and the like is output.

The inverse quantization module 120 and the inverse transform module 130receive the quantization coefficient, perform inverse quantization andinverse transform in order, and a residual signal is output.

The intra prediction module 140 generates a prediction signal byperforming spatial prediction using a pixel value of a pre-decodedneighboring block adjacent to a current decoding block.

The inter prediction module 150 generates a prediction signal byperforming motion compensation using a motion vector extracted from thebitstream and a reconstruction image stored in the reconstructionpicture buffer 180.

The prediction signals output from the intra prediction module 140 andthe inter prediction module 150 are added to a residual signal by theadder 160, and thus a reconstruction signal generated on a per-blockbasis includes the reconstructed image.

The reconstructed image is transmitted to the in-loop filter module 170.A reconstruction picture to which filtering is applied is stored in thereconstruction picture buffer 180, and is used as a reference picture bythe inter prediction module 150.

FIG. 2 is a block diagram illustrating a sequence of decoding avariably-sized quantization group according to an embodiment of thepresent invention.

According to the embodiment of the video decoding apparatus and method,included is at least one of a quantization coefficient group informationdecoding module 210, a quantization coefficient entropy decoding module220, an inverse quantization module 230, an inverse transform module250, and a difference signal obtainment module 260.

The quantization coefficient group information decoding module 210extracts information on the quantization coefficient group from thebitstream.

According to the embodiment, the information on the quantizationcoefficient group includes: whether the variably-sized quantizationgroup is used and the size of the quantization coefficient group; orwhether the variably-sized quantization group is used, the size of thequantization coefficient group, and the partition type of thequantization coefficient group. Also, according to the embodiment, thequantization coefficient group information may be included in a sequenceparameter set, a picture parameter set, a slice header, or a decodingunit, and is transmitted through one or more of the above-describedunits. Also, according to the embodiment, the quantization coefficientgroup is expressed in a flag form, the minimum or maximum size of thequantization coefficient group, a depth type of available size accordingthereto, and the like. Here, the minimum or maximum size is expressed inlog form. The quantization coefficient group information extracted fromthe bitstream by the quantization coefficient group information decodingmodule 210 is transmitted to the quantization coefficient entropydecoding module 220.

The quantization coefficient entropy decoding module 220 operates in adecoding unit, and decodes the encoded quantization coefficient from thebitstream.

According to the embodiment, entropy decoding of the quantizationcoefficients means extracting quantization coefficients which correspondto a current decoding quantization coefficient group, from the bitstreamusing the quantization coefficient group information extracted by thequantization coefficient group information decoding module 210. Also,according to the embodiment, when the quantization coefficients areextracted from the bitstream, an entropy decoding scanning order may usea pre-defined scanning order depending on current quantizationcoefficient group information, or the entropy decoding scanning orderfor the quantization coefficient group is transmitted as additionalinformation.

The inverse quantization module 230 performs inverse quantization on thequantization coefficients extracted by the quantization coefficiententropy decoding module 220.

According to the embodiment, the inverse quantization module performsinverse quantization on the quantization coefficients extracted by thequantization coefficient entropy decoding module 220. However, whenthere is no extracted quantization coefficient and when determining thatquantization is not performed, inverse quantization is not performed.

According to the embodiment, when whether transform is performed 240 isdetermined and determining that transform is performed, the signalextracted by the inverse quantization module 230 is provided to theinverse transform module 250 and the difference signal is obtained bythe inverse transform module. In contrast, when whether transform isperformed 240 is determined and determining that transform is notperformed, the signal extracted by the inverse quantization 230 isdirectly used as the difference signal without going through the inversetransform module 250.

FIG. 3 is a block diagram illustrating a sequence of determining whethera variably-sized quantization coefficient group is decoded and obtainingquantization coefficient group partition information according to anembodiment of the present invention.

According to the embodiment of the video decoding apparatus and method,included is at least one of a variably-sized quantization coefficientgroup usage extraction module 310, a variably-sized quantizationcoefficient group usage determination module 320, a quantizationcoefficient group partition information decoding module 330, and aquantization coefficient entropy decoding module 340.

The variably-sized quantization coefficient group usage extractionmodule 310 extracts information on whether the variably-sizedquantization coefficient group is used.

According to the embodiment, in decoding the quantization coefficientgroup, information on whether the variably-sized quantizationcoefficient group is used is information for determining whether thevariably-sized quantization coefficient group proposed in the presentinvention is used. The information expresses the flag form or the usedpartition type of the variably-sized quantization coefficient group inthe form of a particular value. Also, according to the embodiment,information on whether the variably-sized quantization coefficient groupis used may be included in the sequence parameter set, the pictureparameter set, the slice header, the decoding unit, or the quantizationcoefficient group, and is transmitted through one or more of theabove-described units.

The variably-sized quantization coefficient group usage determinationmodule 320 determines whether the variably-sized quantizationcoefficient group is used, which is extracted by the variably-sizedquantization coefficient group usage extraction module 310.

The quantization coefficient group partition information decoding module330 obtains quantization coefficient group partition information.

According to the embodiment, when determining that the variably-sizedquantization coefficient group is used, the information of thevariably-sized quantization coefficient group is extracted from thebitstream by the quantization coefficient group partition informationdecoding module 330.

According to the embodiment, the information on the quantizationcoefficient group may include: the size of the quantization coefficientgroup; or the size of the quantization coefficient group and thepartition type of the quantization coefficient group. Also, according tothe embodiment, the quantization coefficient group information may beincluded in the sequence parameter set, the picture parameter set, theslice header, the decoding unit, or the quantization coefficient group,and is transmitted through one or more of the above-described units.Also, according to the embodiment, the quantization coefficient groupinformation is expressed in the flag form, the minimum or maximum sizeof the quantization coefficient group, the depth type of available sizeaccording thereto, and the like. Here, the minimum or maximum size isexpressed in log form. The quantization coefficient group informationextracted from the bitstream by the quantization coefficient grouppartition information decoding module 330 is transmitted to thequantization coefficient entropy decoding module 340.

The quantization coefficient entropy decoding module 340 operates in thedecoding unit, and decodes the encoded quantization coefficient from thebitstream.

According to the embodiment, entropy decoding of the quantizationcoefficient means extracting the quantization coefficients whichcorrespond to the current decoding quantization coefficient group, fromthe bitstream using the quantization coefficient group informationextracted from the quantization coefficient group partition informationdecoding module 330. Also, according to the embodiment, when thequantization coefficients are extracted from the bitstream, the entropydecoding scanning order may use the pre-defined scanning order dependingon current quantization coefficient group information, or the entropydecoding scanning order for the quantization coefficient group istransmitted as the additional information.

FIG. 4 is a block diagram illustrating a sequence of decoding using avariably-sized quantization group partition flag according to anembodiment of the present invention.

According to the embodiment of the video decoding apparatus and method,included is at least one of a quantization coefficient group partitionflag extraction module 410, a partition determination module 420, a subquantization coefficient group partition module 430, a quantizationcoefficient group size determination module 440, and a quantizationcoefficient group entropy decoding module 450.

The quantization coefficient group partition flag extraction module 410extracts a flag on whether to partition a current quantizationcoefficient group, from the bitstream in using the variably-sizedquantization coefficient in the quad-tree form.

According to the embodiment, the quantization coefficient group may bepartitioned in the quad-tree form. The quantization coefficient group ina quad-tree partition structure may be a quantization coefficient groupwhich is not partitioned or is partitioned in a recursive partitionstructure with one or more depths.

The partition determination module 420 determines whether to partitionthe current quantization coefficient group on the basis of the flag onwhether to partition the quantization coefficient group, which isextracted by the quantization coefficient group partition flagextraction module 410.

According to the embodiment, when the quantization coefficient group ispartitioned, the sub quantization coefficient group partition module 430operates. Here, the quantization coefficient group partition flagextraction module 410 and the partition determination module 420recursively operate.

According to the embodiment, when the quantization coefficient group isnot partitioned, the quantization coefficient group size determinationmodule 440 determines the size of the current block as the size of thequantization coefficient group, and the quantization coefficient groupentropy decoding module 450 performs entropy decoding on thequantization coefficient group.

FIGS. 5 and 6 are schematic diagrams illustrating examples ofquantization coefficient groups in 4×4 fixed sizes used in aconventional video decoding apparatus and method and scanning orders foran 8×8 decoding block and a 16×16 decoding block using the groups.

The quantization coefficient group in a 4×4 fixed size used in theconventional video decoding apparatus and method uses a scanning orderincluding at least one of a zigzag scanning order 500 and 600, ahorizontal direction scanning order 510, and a vertical directionscanning order 520.

FIG. 7 is a schematic diagram illustrating examples of using a quad-treeconfiguration and multiple scanning orders with respect to avariably-sized quantization coefficient group according to an embodimentof the present invention.

According to the embodiment, in the entropy decoding process of thevariably-sized quantization coefficient group, the scanning orders usedin the conventional video decoding apparatus and method described inFIGS. 5 and 6 are included. The same scanning order 710 is used indifferent quantization coefficient groups within the same decodingblock, or different scanning orders 720 are used.

According to the embodiment, when the quantization coefficients areextracted from the bitstream, the entropy decoding scanning order mayuse the pre-defined scanning order depending on the current quantizationcoefficient group information, or the entropy decoding scanning orderfor the quantization coefficient group is transmitted as the additionalinformation.

FIG. 8 is a schematic diagram illustrating examples of quad-treepartition of a 16×16 decoding block and a 32×32 decoding block for avariably-sized quantization coefficient group according to an embodimentof the present invention.

According to the embodiment of the video decoding apparatus and method,included is quantization coefficient entropy decoding using decodingblocks 810 and 820 that have quantization coefficient groups quad-treepartitioned.

According to the embodiment, the video decoding apparatus and methodinclude an apparatus and method of using decoding blocks 810 and 820which have quantization coefficient groups quad-tree partitioned and anapparatus and method of recursively partitioning a quantizationcoefficient group according to quad-tree partition depth information.The 16×16 decoding block 810 is an example in which a 4×4 quantizationcoefficient group 811 and an 8×8 quantization coefficient group 812 areused according to quad-tree partitioning. The 32×32 decoding block 820is an example in which a 4×4 quantization coefficient group 821, an 8×8quantization coefficient group 822, and a 16×16 quantization coefficientgroup 823 are used according to quad-tree partitioning.

FIG. 9 is a schematic diagram illustrating examples of partitioning avariably-sized quantization coefficient group depending on input signalcharacteristics except for a square shape according to an embodiment ofthe present invention.

According to the embodiment of the video decoding apparatus and method,included are quantization coefficient group partition 910 usingdiagonals and L-shaped quantization coefficient group partition 920.

In FIG. 9, quantization coefficient group partition 910 using diagonalsis an example of partitioning into a low frequency quantizationcoefficient group 1 911, a low frequency quantization coefficient group2 912, a high frequency quantization coefficient group 1 913, and a highfrequency quantization coefficient group 2 914.

According to the embodiment, quantization coefficient group partition910 using diagonals enables quantization coefficient group partitionusing the diagonal 916 with respect to from a low frequency region to ahigh frequency region depending on the characteristics of the inputsignal. According to the embodiment, the number of times of partitioningin quantization coefficient group partition 910 using diagonals uses afixed number or the number of times of partitioning varies by extractionfrom the bitstream.

In FIG. 9, L-shaped quantization coefficient group partition 920 is anexample of partitioning into a low frequency quantization coefficientgroup 1 921, a low frequency quantization coefficient group 2 922, ahigh frequency quantization coefficient group 1 923, and a highfrequency quantization coefficient group 2 924.

According to the embodiment, L-shaped quantization coefficient grouppartition 920 enables quantization coefficient group partition using anL-shaped line 925 with respect to from the low frequency region to thehigh frequency region depending on the characteristics of the inputsignal. According to the embodiment, the number of times of partitioningin L-shaped quantization coefficient group partition 920 is a fixednumber or the number of times of partitioning varies by extraction fromthe bitstream.

FIG. 10 is a schematic diagram illustrating a variably-sizedquantization coefficient group in a non-square shape according to anembodiment of the present invention.

According to the embodiment of the video decoding apparatus and method,a variably-sized quantization coefficient group 1010 in a non-squareshape includes at least one of non-square-shaped horizontal lengthinformation 1010 and vertical length information 1020. Thenon-square-shaped horizontal length information and vertical lengthinformation are derived using partition information in a high-levelquantization coefficient group in a square shape, and thenon-square-shaped horizontal length information and vertical lengthinformation are extracted from the bitstream. According to theembodiment, when using the non-square-shaped horizontal lengthinformation and vertical length information extracted from thebitstream, included is derivation based on values corresponding to thenon-square-shaped horizontal length information and vertical lengthinformation or based on a relation with corresponding index informationand neighboring quantization coefficients.

FIG. 11 is a block diagram illustrating a decoder according to anembodiment of the present invention.

The decoder, which received the bitstream from the encoder, performsdecoding through inter prediction 136-2 and intra prediction 137-2,schematically. According to the embodiment of the present invention, indecoding, when performing inter prediction, inter prediction isperformed through the motion information received from the encoder, orinter prediction is performed through the motion information derived bythe decoder. When performing inter prediction decoding using the motioninformation received from the encoder, a motion prediction module 131calculates a motion vector of an actual corresponding block using aprediction motion vector (PMV) and a received motion vector differencevalue, and performs motion compensation using the calculated motionvector. When the decoder derives a motion vector and the derived motioninformation is used in inter prediction decoding, the motion vector isobtained by a motion derivation module and is used in performing motioncompensation. The method of receiving the motion vector from the encoderor deriving the motion vector by the decoder may be selectively appliedin inter prediction decoding, and selection information and relevantinformation may be received from the encoder through syntax information.

FIG. 12 is a decoding flowchart illustrating a case in which a method ofderiving motion information by the decoder or a method of receiving themotion information from the encoder is selectively applied according toan embodiment of the present invention.

In the flowchart, steps after motion compensation are omitted. Thedecoder derives motion derivation flag (MV_deriv_Flag_(i,j)) informationfrom the input bitstream 201-2. A motion derivation flag 202-2 isselection information on a motion derivation method, and on the basis ofthis, the decoder checks whether to perform decoding using the motionderivation method. The motion information derivation flag generallymeans selection information on the current decoding unit, but, accordingto the embodiment, may indicate the selection of the motion derivationmethod at various levels, such as a sequence, a frame, a frame group, aslice, a slice group, a decoding unit, a decoding unit group, a subdecoding unit, and the like. When the motion derivation flag is a valueof 1, the decoding unit in which encoding is performed using the motionderivation method performs decoding through the motion derivationmethod. Here, the decoder further decodes motion derivation informationon the current decoding unit at step 203-2. The motion derivationinformation on the current decoding unit may include at least oneselected from a group of: depth information on the decoding unit to usethe motion derivation method; information on a method of deriving themotion information in the motion derivation method; information on theshape/size/number of units or sub units to be subjected to motionderivation; and information on the number of iterations. Through one ormore combinations of these types of information, the size, shape, andthe like of the current decoding unit are defined, and motion derivationis performed at step 204-2. The depth information on the decoding unitis such information that information on the size of the block to besubjected to motion derivation at step 204-2 through an actual motionderivation method is found. When the block to which the motionderivation method is applied is 128×128 in size, when the depthinformation is a value of 2, and when the unit is in a square shape,partitioning into sub unit blocks is possible in the shape as shown inFIG. 13(a). This method may be determined by an arrangement between theencoder and the decoder. With the information received from the encoder,partitioning into blocks in predetermined size is possible by thedecoder as shown in FIG. 13(b). When motion information on the currentdecoding unit is derived through motion derivation at step 204-2, theinformation is used in performing motion compensation at step 205-2.

FIG. 14 is a diagram illustrating a method of predicting motioninformation on a current unit using neighboring pixel information on acurrent decoding unit or sub unit according to an embodiment of thepresent invention.

This method is a method in which motion prediction is performed usingthe neighboring pixel information on the unit or sub unit and the resultis used as a motion vector value of the current unit or sub unit. Here,in the current decoding unit, previously decoded regions may be utilizedas regions in which motion prediction may be performed for the currentdecoding unit as shown in FIG. 14(b). Here, when current decoding unitis subjected to motion prediction using the region c-1, motioninformation on the current decoding unit is derived using motionprediction and is used in decoding. In this way, decoding may becompleted. For more precise motion prediction, both a decoded region402-2 and a region 401-2 previously used for motion prediction are usedin performing motion prediction. Here, motion derivation, which isrepeatedly performed, may be determined on the basis of the number ofiterations, which is arranged by the encoder/decoder or information onthe number of iterations, which is transmitted from the encoder to thedecoder. When the current decoding unit is partitioned into sub unitswith the depth information on the decoding unit, motion derivation ofeach sub unit is possible using pieces of gray-shaded information shownin FIG. 14(d). As one embodiment, through an arrangement between thedecoder and the encoder, the size, shape of the gray-shaded portionsubjected to motion prediction may vary. Information thereon may includethe value and shape fixed by the arrangement of the encoder/decoder, andthere is a method of transmitting the information from the encoder tothe decoder. The method of deriving the motion information on thecurrent block using the neighboring pixel information is applicable toone or more reference images as shown in FIG. 15. When using multiplereference images, the motion vector value may be calculated by a commonmethod used in video decoding. Here, examples of the common methodinclude a method of calculating a motion value in proportion to a timedifference value according to the time order of the reference images andthe current decoding image.

FIG. 16 is a diagram illustrating a method of deriving motioninformation of a current decoding unit using values of co-located blocksof the current decoding unit or sub unit according to an embodiment ofthe present invention. In general, a motion vector is calculated througha method of minimizing errors between co-located blocks in two or morereference images based on the current decoding unit. This method is alsoa method of predicting motion information on the current unit usingneighboring pixel information. Various methods are possible throughcombinations of the information on the method of deriving the motioninformation, the shape of the unit or subunit to be subjected to motionderivation, the number of iterations, and the like.

FIG. 17 is a diagram illustrating a decoding apparatus that performsglobal motion compensation according to an embodiment of the presentinvention.

The decoding apparatus that performs global motion compensation mayinclude at least one of an entropy decoding module 110-3, an inversequantization module 120-3, an inverse transform module 130-3, an interprediction module 140-3, an intra prediction module 150-3, an in-loopfilter module 160-3, and a reconstruction image storage module 170-3.

The entropy decoding module 110-3 outputs decoding information such assyntax elements, a quantized coefficient, and the like by decoding theinput bitstream 100-3. The output information may include informationfor global motion compensation.

The inverse quantization module 120-3 and the inverse transform module130-3 receive the quantization coefficient, and perform inversequantization and inverse transform in order, and the residual signal isoutput.

The inter prediction module 140-3 generates the prediction signal byperforming motion compensation using the motion vector extracted fromthe bitstream and the reconstruction image stored in the reconstructionimage storage module 170-3. The inter prediction module 140-3 performsglobal motion compensation on the global motion compensation regionusing information 190 for global motion compensation.

The intra prediction module 150-3 generates the prediction signal byperforming spatial prediction using the pixel value of the pre-decodedneighboring block adjacent to the current decoding block.

The prediction signals output from the inter prediction module 140-3 andthe intra prediction module 150-3 is added to the residual signal, andthe reconstructed image generated through adding is transmitted to thein-loop filter module 160-3.

The reconstruction picture to which filtering is applied by the in-loopfilter module 160-3 is stored in the reconstruction image storage module170-3, and is used as a reference picture by the prediction module140-3. The reconstruction image 180-3 is output from the reconstructionimage storage module 170-3.

FIG. 18 is a diagram illustrating a method of performing global motioncompensation on an image according to an embodiment of the presentinvention.

Global motion compensation may be performed on an extensive region 210-3of an image 200-3 at once. In the process of reconstructing the image, aglobal motion compensation region 210-3 is determined, and motioncompensation is performed at once on the determined global motioncompensation region 210-3. The global motion compensation region 210-3may be determined by the additional information transmitted to thedecoder.

FIG. 19 is a block diagram illustrating a sequence of a method ofperforming global motion compensation according to an embodiment of thepresent invention.

First, global motion compensation information is extracted from thebitstream at step 310-3. The extracted information is used to determinethe global motion compensation region at step 320-3. By using thedetermined motion compensation region information, when the region issubjected to global motion compensation in the image, global motioncompensation is performed at step 330-3 and the reconstruction image isgenerated at step 350-3. When the region is not subjected to globalmotion compensation, decoding on a per-block basis is performed at step340-3 and the reconstruction image is generated at step 350-3.

FIG. 20 is a diagram illustrating a method of determining a final globalmotion compensation region using information indicating an inside or anoutside of a region determined as the global motion compensation regionamong pieces of information transmitted to the decoder, when performingglobal motion compensation according to an embodiment of the presentinvention.

By using global motion compensation region determination informationincluded in information transmitted to the decoder, the global motioncompensation region in the image is determined. By informationindicating an inside or an outside of the determined global motioncompensation region, the final global motion compensation region isdetermined. The information indicating the inside or the outside of theglobal motion compensation region may be transmitted in the flag form.

In FIG. 20, when a final global motion compensation region determinationflag is a value of 0, the final global motion compensation region in theimage is the inside 420-3 of the determined motion compensation region410-3. When the final global motion compensation region determinationflag is a value of 1, the final global motion compensation region of theimage is the outside 440-3 of the determined motion compensation region430-3.

FIG. 21 is a diagram illustrating global motion compensation regions invarious shapes when performing global motion compensation according toan embodiment of the present invention.

The global motion compensation regions 510-3, 520-3, and 530-3 may beprovided in arbitrary shape, and multiple global motion compensationregions 510-3, 520-3, and 530-3 may be used within one image.

When multiple global motion compensation regions are used within oneimage, the motion compensation region is determined using individualinformation transmitted to each motion compensation region, or referringto information on another motion compensation region.

FIG. 22 is a diagram illustrating a method of determining a globalmotion compensation region according to boundaries on a per-coding unitbasis when performing global motion compensation according to anembodiment of the present invention.

The global motion compensation regions may be determined as markedregions 610-3 and 620-3 according to boundaries on a per-decoding blockbasis.

Also, the global motion compensation regions may be partitioned blockssuch as decoding blocks 610-3 and 620-3 hierarchically partitioned.

The information on the global motion compensation region is included ineach decoding block, or information on each decoding block is includedin each global motion compensation region.

FIG. 23 is a diagram illustrating a method of determining a position ofa global motion compensation region when performing global motioncompensation according to an embodiment of the present invention.

Methods of determining the position of the global motion compensationregion include a determination method 710-3 using coordinates of a startpoint (x, y) and an end point (x′, y′) of the region and a determinationmethod 720-3 using coordinates of the start point (x, y) and thehorizontal length (width) and vertical length (height) of the region.

FIG. 24 is a diagram illustrating a method of determining a globalmotion compensation region by merging sections obtained throughpartition in a grid shape, when performing global motion compensationaccording to an embodiment of the present invention.

As a method of determining the global motion compensation region, thereis a method of determining the global motion compensation region bypartitioning the image into several sections in the grid shape and bymerging each separated region with another region. A block 810-3, block820-3, block 830-3, block 840-3, and block 850-3 are merged with a blockin the direction the arrows points such that the global motioncompensation region is reached. The block 850-3 is merged with the block840-3 with reference thereto, the block 840-3 is merged with the block830-3 with reference thereto, the block 830-3 is merged with the block820-3 with reference thereto, and the block 820-3 is merged with theblock 810-3 with reference thereto, thereby constructing the globalmotion compensation region.

FIG. 25 is a diagram illustrating a method of determining a globalmotion compensation region by repeatedly partitioning an image in ahorizontal or vertical direction, when performing global motioncompensation according to an embodiment of the present invention.

The global motion compensation region may be determined by repeatedlypartitioning the image in the vertical or horizontal direction.

As shown in FIG. 25, the image may be partitioned according to thehorizontal boundary 910-3 first, and then partitioned according to thevertical boundary 920-3. The region 910-2-3 obtained after partitionaccording to the horizontal boundary 910-3 is a region which is nofurther partitioned, and the region 920-1-3 obtained after partitionaccording to the vertical boundary 920-3 is also a region which is nofurther partitioned. Repeated partitioning is possible according to thehorizontal boundary 950-3, the vertical boundary 970-3, and the verticalboundary 990-3. The region 950-1-3 obtained by partition according tothe horizontal boundary 950-3 and the region 970-1-3 obtained bypartition according to the vertical boundary 970-3 are regions which areno further partitioned.

The encoder may transmit information on boundaries for partition, andthe decoder may determine the global motion compensation region usingthe received information on the boundaries.

FIG. 26 is a diagram illustrating a method of determining a globalmotion compensation region using a warping parameter in additioninformation transmitted to a decoder when performing global motioncompensation according to an embodiment of the present invention.

When an object 1010-3 is warped 1020-3 in two images at temporallydifferent viewpoints, the encoder transmits a warping parameter to thedecoder, and the decoder determines the motion compensation region usingthe received warping parameter.

FIG. 27 is a diagram illustrating a method of rotating or scaling aglobal motion compensation region when performing global motioncompensation according to an embodiment of the present invention.

When an object 1110-3 is scaled 1120-3 or rotated 1130-3 in two imagesat temporally different viewpoints, the encoder transmits scalinginformation or information on the rotated region to the decoder, and thedecoder determines the motion compensation region using the receivedinformation.

FIG. 28 is a diagram illustrating a case in which a frame rate upconversion (FRUC) method for increasing a frame rate is used whenperforming global motion compensation according to an embodiment of thepresent invention.

When performing the frame rate up conversion (FRUC) method on the imagesubjected to global motion compensation, synthesizing of a new framebetween two frames through motion estimation on a per-block basis aswell as synthesizing of a new frame through motion estimation on aper-global motion compensation region basis are possible.

In FIG. 28, when generating an image T-½ between a previous image T-1and a subsequent image T, a synthesized block 1220-3 is generated usingthe block 1210-3 of the previous image and the block 1230-3 of thesubsequent image, or a synthesized global motion region 1250-3 isgenerated using the global motion region 1240-3 of the previous imageand the global motion region 1260-3 of the subsequent image.

FIG. 29 is a diagram illustrating a video decoding apparatus capable ofgenerating an intra prediction signal using intra prediction informationin an encoded bitstream and of outputting a reconstruction image usingthe generated intra prediction signal according to an embodiment of thepresent invention.

The input encoded bitstream 101-4 is decoded by an entropy decodingmodule 102-4. The residual signal is reconstructed through an inversequantization module 103-4 and an inverse transform module 104-4. Anintra prediction module 106-4 may perform intra prediction using thereconstruction signal for intra prediction generated by a predictionsignal generation module 105-4. The prediction signal generation module105-4 may perform a process of removing a portion of a high frequencycomponent by applying a low-pass filter to the reconstruction signal forintra prediction. The motion compensation module 107-4 may perform interprediction using the reconstruction signal of previous time stored in areconstruction image storage module 109-4. The prediction signalgenerated through intra prediction or inter prediction and the residualsignal are used in generating the reconstruction signal, and a filter isapplied to the generated reconstruction signal through an in-loop filtermodule 108-4. The result may be stored in the reconstruction imagestorage module 109-4 to be referenced in the later picture, and may beoutput as a reconstruction image 110-4 according to output order ofimages.

FIG. 30 is a diagram illustrating a referable region for an intraprediction block according to an embodiment of the present invention.

For intra prediction of a current intra prediction block 201-4 in an M×Nsize, a top left reference pixel 202-4, a top reference pixel column203-4, and a left reference pixel column 204-4 may be used. The topreference pixel column 203-4 may be longer than the horizontal length Nof the intra prediction block and may be (n*N) in length with respect ton which larger than 1. The left reference pixel column 204-4 may belonger than the vertical length M of the intra prediction block and maybe (m*M) in length with respect to m which is larger than 1.

FIG. 31 is a diagram illustrating a method of performing directionalintra prediction depending on a length of a top reference pixel columnaccording to an intra prediction method according to an embodiment ofthe present invention.

For intra prediction of a current intra prediction block 301-4 in an M×Nsize, when a referable top reference pixel column 302-4 is longer than2N in length, regarding directional intra prediction of the intraprediction block 301-4, intra prediction is performed using directionalintra prediction 304-4 of which an angle 303-4 is smaller than an angleof 45 degrees.

FIG. 32 is a diagram illustrating a method of performing directionalintra prediction depending on a length of a left reference pixel columnaccording to an intra prediction method according to an embodiment ofthe present invention.

For intra prediction of a current intra prediction block 401-4 in an M×Nsize, when a referable left reference pixel column 402-4 is longer than2M in length, regarding directional intra prediction of the intraprediction block 401-4, intra prediction is performed using directionalintra prediction 404-4 of which an angle 403-4 is larger than an angleof 315 degrees.

FIG. 33 is a diagram illustrating ranges of applicable directionalprediction in an intra prediction method according to an embodiment ofthe present invention.

In the proposed intra prediction method, applicable directionalprediction is on the basis of a range of directional prediction with anangle ranging from 45 degrees to 315 degrees including a predictionrange 1 501-4, a prediction range 2 502-4, and a prediction range 3503-4. When with respect to a horizontal length N of a current intraprediction block, a top reference pixel column is longer than 2N inlength, intra prediction is performed in a directional prediction modeof one of ranges corresponding to the prediction range 1 501-4, theprediction range 3 503-4, and the prediction range 5 505-4. When withrespect to a vertical length M of a current intra prediction block, aleft reference pixel column is longer than 2M in length, intraprediction is performed in a direction prediction mode of one of rangescorresponding to the prediction range 1 501-4, the prediction range 2502-4, and the prediction range 4 504-4. The prediction range dependingon the length of the reference pixel column may be adaptively determinedaccording to whether the reference pixel column is decoded or not.Alternatively, through a syntax element, a prediction range to be usedfor intra prediction of the current intra prediction block may besignaled.

FIG. 34 is a diagram illustrating a method of generating an intraprediction signal by varying the brightness of a pixel with the sameslope as a reconstruction pixel region from a signal of a reconstructionpixel region depending on pixel coordinates of a non-reconstructionpixel region in an intra prediction method according to an embodiment ofthe present invention.

With respect to a reconstruction pixel region 601-4 included in areconstructed neighboring block adjacent to a current intra predictionblock, when there is a non-reconstruction pixel region 602-4 adjacent tothe reconstruction pixel region continually, the prediction signal isgenerated in such a manner that a variation in a pixel value at aposition spaced apart from a start position of the reconstruction pixelregion by a predetermined offset 603-4 is equal to a variation in apixel value at a position spaced apart from a start position of thenon-reconstruction pixel region by an offset 604-4 which is the same asthe above-described offset. After, signal of the reconstruction pixelregion 601-4 and the newly generated non-reconstruction pixel region602-4 may be referenced for intra prediction.

FIG. 35 is a diagram illustrating a method of generating an intraprediction signal by varying a brightness of a pixel with a negativeslope having the same size as a reconstruction pixel region depending onpixel coordinates of a non-reconstruction pixel region from a signal ofa neighboring reconstruction pixel region in an intra prediction methodaccording to an embodiment of the present invention.

With respect to a reconstruction pixel region 701-4 included in areconstructed neighboring block adjacent to a current intra predictionblock, when there is a non-reconstruction pixel region 702-4 adjacent tothe reconstruction pixel region continually, the prediction signal isgenerated in such a manner that a variation in a pixel value at aposition spaced apart from an end position of the reconstruction pixelregion by a predetermined offset 703-4 is equal to a variation in apixel value at a position spaced apart from a start position of thenon-reconstruction pixel region by an offset 704-4 which is the same asthe above-described offset and the signs of the slopes are opposite toeach other. After, signals of the reconstruction pixel region 701-4 andthe newly generated non-reconstruction pixel region 702-4 may bereferenced for intra prediction.

FIG. 36 is a diagram illustrating another method of generating an intraprediction signal by varying a brightness of a pixel with the same slopeas a reconstruction pixel region from a signal of a neighboringreconstruction pixel region depending on pixel coordinates of anon-reconstruction pixel region in an intra prediction method accordingto an embodiment of the present invention.

With respect to a reconstruction pixel region (801-4) included in areconstructed neighboring block adjacent to a current intra predictionblock, when there is a non-reconstruction pixel region 802-4 adjacent tothe reconstruction pixel region continually, the prediction signal isgenerated in such a manner that a variation in a pixel value at aposition spaced apart from an end position of the reconstruction pixelregion by a predetermined offset 803-4 is equal to a variation in apixel value at a position spaced apart from a start position of thenon-reconstruction pixel region by an offset 804-4 which is the same asthe above-described offset. After, signals of the reconstruction pixelregion 801-4 and the newly generated non-reconstruction pixel region802-4 may be referenced for intra prediction.

FIG. 37 is a diagram illustrating a method of signaling whether intraprediction is performed, which is proposed by a sequence parameter setof a high-level syntax for an intra prediction method according to anembodiment of the present invention.

In the proposed intra prediction method, whether it is possible to applythe proposed intra prediction method within a sequence parameter set 901among network abstract layer (NAL( ) units existing in a compressionbitstream is expressed in the form of a 1-bit flag 902-4“seq_model_intra_enabled_flag”. When the value of the relevant flag istrue, pictures that refer to the sequence parameter set are decodedusing the proposed intra prediction method.

FIG. 38 is a diagram illustrating a method of signaling whether intraprediction is performed which is proposed by a picture parameter set ofa high-level syntax for an intra prediction method according to anembodiment of the present invention.

In the proposed intra prediction method, whether it is possible to applythe proposed intra prediction method within a picture parameter set1001-4 among network abstract layer (NAL) units existing in acompression bitstream is expressed in the form of a 1-bit flag 1002-4“pic_model_intra_enabled_flag”. When the value of the relevant flag istrue, slices that refer to the picture parameter set are decoded usingthe proposed intra prediction method. Also, when the value of“pic_model_intra_enabled_flag” transmitted within the picture parameterset is true, whether it is possible to apply the proposed intraprediction method to intra prediction blocks in all sizes allowablewithin a picture is expressed in the form of a 1-bit flag 1003-4“pic_model_intra_all_blk_sizes_flag”. When the value ofpic_model_intra_enabled_flag is true and the value ofpic_model_intra_all_blk_sizes_flag is false, among the intra predictionblocks included in the current picture, min_log 2_model_intra_blk_size1004-4 and max_log 2_model_intra_blk_size 1005-4 which are log values tobase 2 of the minimum size and the maximum size of blocks to which theproposed intra prediction method is possibly applied are transmitted inthe form of an exponential-Golomb code.

FIG. 39 is a diagram illustrating a method of signaling whether intraprediction is performed which is proposed by a slice segment header of ahigh-level syntax for an intra prediction method according to anembodiment of the present invention.

In the proposed intra prediction, whether it is possible to apply theproposed intra prediction method within a slice segment header 1101-4among network abstract layer (NAL) units existing in a compressionbitstream is expressed in the form of a 1-bit flag 1102-4slice_model_intra_enabled_flag. When the value of the relevant flag istrue, blocks that refer to the slice segment header are decided usingthe proposed intra prediction method.

FIG. 40 is a diagram illustrating a decoding apparatus including anintra prediction module according to an embodiment of the presentinvention.

The decoding apparatus which including the intra prediction module mayinclude at least one of an entropy decoding module 110-5, an inversequantization module 120-5, an inverse transform module 130-5, an intraprediction module 140-5, an inter prediction module 150-5, an in-loopfilter module 160-5, and a reconstruction image storage module 170-5.

The entropy decoding module 110-5 outputs decoding information, such assyntax elements, the quantized coefficient, and the like, by decodingthe input bitstream 100-5. The output information may includeinformation for global motion compensation.

The inverse quantization module 120-5 and the inverse transform module130-5 receive the quantization coefficient and perform inversequantization and inverse transform in order, and the residual signal isoutput.

The intra prediction module 140-5 generates the prediction signal byperforming spatial prediction using the pixel value of the pre-decodedneighboring block adjacent to the current decoding block. A neighboringpixel value in a curve direction may be used for prediction signalgeneration.

The inter prediction module 150-5 generates the prediction signal byperforming motion compensation using the motion vector extracted fromthe bitstream and the reconstruction image stored in the reconstructionimage storage module 170-5.

The prediction signals output from the intra prediction module 140-5 andthe inter prediction module 150-5 are added to the residual signal, andthus the reconstructed image generated through adding is transmitted tothe in-loop filter module 160-5.

The reconstruction picture to which filtering is applied by the in-loopfilter module 160-5 is stored in the reconstruction image storage module170-5, and is used as a reference picture by the inter prediction module150-5.

FIG. 41 is a diagram illustrating neighboring reference regions whenperforming intra prediction according to an embodiment of the presentinvention.

In order to generate a prediction sample of a current intra predictionblock 210-5 in an M×N size, a top reference sample 220-5, a leftreference sample 230-5, and a top left reference sample 240-5 may beused.

The length of the top reference sample 220-5 column may be longer thanthe horizontal length M of the current intra prediction block 210-5.Also, the length of the left reference sample 230-5 column may be longerthan the vertical length N of the current intra prediction block 210.

FIG. 42 is a diagram illustrating a method of referring to a pixel of aneighboring block when performing intra prediction according to anembodiment of the present invention.

When generating a prediction sample of a current intra prediction block310-5 in an M×N size, the prediction signal is generated using areference sample in a curve 320-5 direction. The curve is expressed inan N-th degree equation, or may be a straight line depending on acoefficient.

Information on the curve may be transmitted as being included in thebitstream, and the information may include a degree or a coefficient ofa curve equation.

FIG. 43 is a diagram illustrating a method of referring to multiplepixels of a neighboring block when performing intra prediction accordingto an embodiment of the present invention.

When generating a prediction sample 420-5 of a current intra predictionblock 410-5 in an M×N size, one or two or more pixels of a neighboringblock in a curve 430-5 direction may be referenced.

When using two or more reference samples, the prediction sample 420-5 isgenerated with a weighted average value of reference samples 440-5 and450-5.

FIG. 44 is a diagram illustrating a method of generating a non-existingreference sample in a neighboring block, when performing intraprediction according to an embodiment of the present invention.

When a reference sample is partially present near a current intraprediction block 510-5 in an M×N size, a non-existing reference sampleis generated using available reference samples 540-5 and 550-5.

When generating non-existing reference samples 520-5 and 530-5, thelength of the reference sample to be generated may differ depending on acurve 560 used in the current prediction block.

FIG. 45 is a diagram illustrating a method of performing predictionusing reference samples in different directions in respective regions ofa prediction block, when performing intra prediction according to anembodiment of the present invention.

When a current intra prediction block in an M×N size is divided into twosections A and B by this curve 610-5, prediction samples are generatedin the sections A and B using reference samples in different directions.

One or more reference samples may be used to generate the predictionsample in the section A or section B, and one or more reference samplesmay be positioned in different directions.

FIG. 46 is a diagram illustrating another method of performingprediction using reference samples in different directions in respectiveregions of a prediction block, when performing intra predictionaccording to an embodiment of the present invention.

When a current intra prediction block in an M×N size is divided intosections A, B, C, and D by a curve 710-5 and a straight line 720-5connecting edges of the block, prediction samples are generated in thesections A, B, C, and D using reference samples in different directions.

One or more reference samples may be used to generate the predictionsample in each of the sections A, B, C, and D, and one or more referencesamples may be positioned in different directions.

FIG. 47 is a diagram illustrating a method of performing filtering on aleftmost prediction sample column of a prediction block so as to removediscontinuity to a neighboring block, when performing intra predictionaccording to an embodiment of the present invention.

Among regions obtained by dividing a current intra prediction block inan M×N size with a curve or straight line, when a region subjected tovertical direction prediction is positioned on the left of theprediction block, filtering is performed on a prediction sample in aleftmost column of the prediction block.

When performing filtering on samples in the leftmost column of theprediction block, a left reference sample variation is used.

For example, as shown in FIG. 47, prediction block is divided into tworegions A and B by a curve 810-5. When the region A is subjected tovertical direction prediction, filtering is performed on predictionsamples in the leftmost column 820-5 using a variation 830-5 in leftreference samples.

FIG. 48 is a diagram illustrating a method of filtering a topmostprediction sample column of a prediction block so as to removediscontinuity to a neighboring block, when performing intra predictionaccording to an embodiment of the present invention.

Among regions obtained by dividing a current intra prediction block inan M×N size with a curve or straight line, when a region subjected tohorizontal direction prediction is positioned on the top of theprediction block, filtering is performed on a prediction sample in thetopmost column of the prediction block.

When performing filtering on samples in the topmost column of theprediction block, a top reference sample variation is used.

For example, as shown in FIG. 48, when the prediction block is dividedinto two regions A and B by a curve 910-5, and the region A is subjectedto horizontal direction prediction, filtering is performed on predictionsamples in the topmost column 920-5 using a variation 930-5 in topreference samples.

FIG. 49 is a flowchart illustrating a sequence of performing intraprediction according to an embodiment of the present invention.

First, curve intra prediction information is extracted from thebitstream at step 1010-5. The extracted information may include a degreeor coefficient of a curve equation for a curve equation for expressingthe curve. By using the extracted information on the curve andinformation on whether the reference pixel of the neighboring block ispresent, whether reference sample padding is required is determined atstep 1020-5. When reference sample padding is required, a non-existingreference sample is generated at step 1030-5 using an availablereference sample of a neighboring block. When reference sample paddingis not required, the prediction sample of the current intra predictionblock is generated at step 1040-5 using the reference sample. Ingenerating the prediction sample, the reference sample is determinedusing the extracted information on the curve. When generation of theprediction block is completed, whether to perform filtering on theprediction sample is determined at step 1050-5. Since the left region ofthe prediction block is subjected to vertical direction prediction orthe top region of the prediction block is subjected to horizontaldirection prediction, when filtering on the prediction sample isrequired, prediction sample filtering is performed at step 1060-5 usingthe variation in the neighboring reference sample. Filtering for theprediction sample may be performed on the leftmost sample column and thetopmost sample row of the prediction block.

INDUSTRIAL APPLICABILITY

The present invention may be used in encoding/decoding a video signal.

What is claimed is:
 1. A video decoding method, performed by a videodecoding apparatus, comprising: obtaining sub-group usage informationindicating whether sub-group partitioning is usable for a sequence, thesub-group usage information being obtained from a sequence parameter setof a bitstream; obtaining, based on the sub-group usage information,partition type information of a current coding unit from the bitstream,wherein the partition type information includes a partition flagindicating whether the current coding unit is partitioned into aplurality of sub-groups and partition direction information indicatingwhether the current coding unit is partitioned in a horizontal directionor in a vertical direction; and decoding the current coding unit basedon the partition flag, wherein the partition flag equal to 1 indicatesthat the current coding unit is partitioned into the plurality of thesub-groups, and the partition flag equal to 0 indicates that the currentcoding unit is not partitioned into the plurality of the sub-groups,wherein, in response to the partition flag equal to 1, a number of thesub-groups resulting from partitioning the current coding unit isadaptively determined based on a size of the current coding unit,wherein, in response to the current coding unit with the partition flagequal to 1, coefficients of the current coding unit is scanned using afirst scan order among a plurality of scan orders pre-defined in adecoding apparatus, and wherein, in response to the current coding unitwith the partition flag equal to 0, the coefficients of the currentcoding unit is scanned using a second scan order among the plurality ofthe scan orders pre-defined in the decoding apparatus.
 2. The method ofclaim 1, wherein, when the partition flag indicates that the currentcoding unit is not partitioned, the current coding unit isinverse-quantized based on the sub-group having a same size as thecurrent coding unit.
 3. The method of claim 1, wherein, when thepartition direction information indicates that the current coding unitis horizontally partitioned, the current coding unit isinverse-quantized based on at least two sub-groups resulting frompartitioning the current coding unit horizontally.
 4. The method ofclaim 1, wherein, when the partition direction information indicatesthat the current coding unit is vertically partitioned, the currentcoding unit is inverse-quantized based on at least two sub-groupsresulting from partitioning the current coding unit vertically.
 5. Avideo encoding method, performed by a video encoding apparatus,comprising: determining whether sub-group partitioning is usable for asequence; determining a partition type of a current coding unit inresponse to a case where the sub-group partitioning of a coding unit isusable for the sequence; and encoding the current coding unit based onthe determined partition type, wherein sub-group usage information isencoded, based on a result of determining whether the sub-grouppartitioning is usable for the sequence, into a sequence parameter setof a bitstream, wherein partition type information is encoded, based onthe determined partition type, into a bitstream, wherein the partitiontype information includes a partition flag indicating whether thecurrent coding unit is partitioned into a plurality of sub-groups andpartition direction information indicating whether the current codingunit is partitioned in a horizontal direction or in a verticaldirection, wherein the partition flag equal to 1 indicates that thecurrent coding unit is partitioned into the plurality of the sub-groups,and the partition flag equal to 0 indicates that the current coding unitis not partitioned into the plurality of the sub-groups, wherein, inresponse to the partition flag equal to 1, a number of the sub-groupsresulting from partitioning the current coding unit is adaptivelydetermined based on a size of the current coding unit, wherein, inresponse to the current coding unit with the partition flag equal to 1,coefficients of the current coding unit is scanned using a first scanorder among a plurality of scan orders pre-defined in an encodingapparatus, and wherein, in response to the current coding unit with thepartition flag equal to 0, the coefficients of the current coding unitis scanned using a second scan order among the plurality of the scanorders pre-defined in the encoding apparatus.
 6. A non-transitorycomputer-readable medium for storing a bitstream associated with a videosignal, wherein the bitstream includes sub-group usage informationindicating whether sub-group partitioning is usable for a sequence andpartition type information of a current coding unit, wherein thesub-group usage information is included in a sequence parameter set ofthe bitstream, wherein the partition type information is obtained basedon the sub-group usage information, wherein the partition typeinformation includes a partition flag indicating whether the currentcoding unit is partitioned into a plurality of sub-groups and partitiondirection information indicating whether the current coding unit ispartitioned in a horizontal direction or in a vertical direction,wherein the partition flag equal to 1 indicates that the current codingunit is partitioned into the plurality of the sub-groups, and thepartition flag equal to 0 indicates that the current coding unit is notpartitioned into the plurality of the sub-groups, wherein, in responseto the partition flag equal to 1, a number of the sub-groups resultingfrom partitioning the current coding unit is adaptively determined basedon a size of the current coding unit, wherein, in response to thecurrent coding unit with the partition flag equal to 1, coefficients ofthe current coding unit is scanned using a first scan order among aplurality of pre-defined scan orders, and wherein, in response to thecurrent coding unit with the partition flag equal to 0, the coefficientsof the current coding unit is scanned using a second scan order amongthe plurality of the pre-defined scan orders.